1. Technical Field
The present disclosure relates to endoluminal vascular prostheses and methods of placing such prostheses, and, in one application, to endoluminal vascular prostheses for use in the treatment of Type II endoleaks.
2. Background
Stent grafts can be used for the endovascular treatment of aortic disease including aneurysms and dissections. The purpose of the stent graft is generally to isolate the diseased portion of the aortic wall from the aortic blood pressure and prevent further dilatation or rupture of the diseased portion of the aortic wall.
FIG. 1 shows an infrarenal abdominal aneurysm. The aorta 4 is enlarged below the renal arteries 2a, 2b and above the iliac arteries 3a, 3b. The enlarged aorta has formed an aneurysm sac 1. Pairs of lumbar arteries 5a, 5b branch from the aorta 4 in the region of the aneurysm sac 1.
FIG. 2 shows a bifurcated stent graft 10 placed in the aorta 4 to exclude the aneurysm sac 1 from the arterial blood pressure. The stent graft 10 creates a proximal seal distal to the renal arteries 2a, 2b and a distal seal 3a, 3b in the iliac arteries. An incomplete seal creates leakage flow from the aorta 4 into the aneurysm sac 1 and into the lumbar arteries 5a, 5b. A leak at the proximal or distal seal of the stent graft 10 is referred to as a Type I endoleak. A leak between overlapping components of the stent graft system 1 is referred to as a Type III endoleak. A leak through the covering of the stent graft is referred to as a Type IV endoleak. Type I, III, and IV are influenced by the specific design features of the stent graft 10.
There also exists a type of endoleak that is independent of the stent graft 10. The leak is created by pressure differences in the lumbar arteries 5a, 5b. FIG. 3 illustrates a leakage flow from a first pair of lumbar arteries 5a to a second pair of lumbar arteries 5b wherein the blood pressure in the first pair of lumbar arteries 5a is greater than that in the second pair of lumbar arteries 5b. This type of leak is referred to as Type II endoleak.
Current stent graft systems do not address the issue of Type II endoleaks. Type II endoleaks are present in a considerable number of patients after stent graft placement. These endoleaks can potentially cause continuing dilatation and even rupture of the aneurysm in some patients.
Various strategies have been developed to manage Type II endoleaks. In general, patients are monitored and their aneurysms are imaged routinely to ensure stabilization of the aneurysm. In case of persistent Type II endoleaks associated with aneurysm dilatation, interventions are recommended to embolize the endoleak. Coils or fast-curing polymers can be injected into the aneurismal sac to thrombose the blood in the sac and stop the blood flow between the lumbar arteries.
There is a clear need to manage Type II endoleaks. The current invention proposes a novel design of a stent graft that eliminates Type II endoleaks at the time of stent graft placement.